1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', 'pjfl4ktt83jitqb4qc5v9np1f7', '216.73.216.147', '1751763643', '1751763643', '/shop_content.php?coID=8&XTCsid=e990f3916c880610adc34c2fa7d30f83')

[XT SQL Error]